The invention relates to the dimensional and physicochemical characterization of any material, used in a progressive cavity pump, which could have its mechanical, physical, chemical, and dimensional properties altered over time by the pumped fluid.
This characterization may, for example, provide an understanding of the swelling of the elastomer forming the stator under the environmental conditions in which the pump is to be used, in order to achieve the best rotor-stator engagement. When this engagement is insufficient, hydraulic pump efficiency is degraded. Conversely, when this engagement is too tight, the friction caused by the excessive engagement heats the elastomer, leading to a change in its mechanical properties. This change results in premature aging, degradation, and loss of functional properties of the pump or even destruction of the stator.
It is known to characterize the materials used in a progressive cavity pump by “off-site” or “ex situ” tests. However, the environmental conditions existing downhole (pressure, temperature, chemical composition, acidity . . . ), sometimes several kilometers from the surface, are not really known and are difficult to reproduce in the laboratory. To overcome this disadvantage, some tests such as aging tests are performed with fluid samples pumped from a well, pipe, pipeline, tank, etc. However, many components (gas, volatile materials) are lost during the transfer of the pumped fluid from its original environment to the characterization laboratory, rendering the tests more or less approximate. In addition, the existing environmental conditions downhole (pressure, temperature, chemical composition, acidity) vary as the well matures. These environmental conditions also vary from one well to another.
As a result, characterizing materials by using such “ex situ” tests is unsatisfactory because it is too approximate.